Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with
       ▸ 07.93: Cable V.A.G 1551/1
       08.93 ▸: Cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/18
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram
• ◆ Chilling spray (commercially available)

Test sequence

Engine codes ABD 02.93 ▸, ABU, AEA

Engine codes ABD ▸01.93

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01); carry out selection with ignition switched on.
  => Page 01-4

• ‒ Input 08 for "Read measured value block" function and confirm with Q.

• ‒ Input 02 for "Display group number" and confirm with Q.

• ‒ Note intake air temperature figure in display zone 4.

     1)     If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check sender wiring for transfer resistances.

Continuation of check when display = -55 °C:

• ‒ Remove air intake elbow.

• ‒ → Pull 4 pin connector -1- off injection unit -2- (engine code ABD: Front connector).
• ‒ Bridge following contacts on connector with aux. cables from V.A.G 1594:
       Engine code ABD: Contacts 1+4
       (broken line)
       Engine codes ABU, AEA: Contacts 1+2

Display approx. 130 °C or higher:

• ‒ Replace injector bracket with intake air temperature sender (G42) , item 7 .

Display approx. -55 °C:

• ‒ Press ⇒ button.

• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition
• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

• ‒ Check wire between test box socket 43+4 pin connector
       Engine code ABD: Contact 4
       Engine code ABU, AEA: Contact 2
  for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wire for short to battery positive.
       Specification: ∞ω
• ‒ Check wire between test box socket 17+4 pin connector contact 1 for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω

If no fault in wire is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 2 .

Continuation of check when display = 130 °C or higher:

• ‒ Remove air intake elbow.
• ‒ → Pull 4 pin connector -1- off injection unit -2- (engine code ABD: Front connector).

Display approx. -55 °C:

• ‒ Replace injector bracket with intake air temperature sender (G42) , item 7 .

Display approx. 130 °C or higher:

• ‒ Press ⇒ button.
• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition
• ‒ Pull connector off Mono Motronic control unit.
• ‒ Check wiring to control unit connector at 4 pin connector
       Engine code ABD: Contact 4
       Engine code ABU, AEA: Contact 2
  for short to wire contact 1 and to vehicle earth.
       Specification: ∞ω

If no wiring fault is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 2 .

Continuation of check when display = ambient temperature:

• ‒ Remove air intake elbow.
• ‒ Note intake air temperature figure in display zone 4.

• ‒ → Spray sender arrow with a commercial chilling spray and at the same time observe the temperature figure. The temperature figure must
       decrease.
• ‒ Press ⇒ button.
• ‒ Input 06 for "End output" and confirm with Q.

Engine code ABD ▸ 01.93

• ‒ Remove air cleaner cover.
• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01); carry out selection at idling.
  => Page 01-4

• ‒ Input 08 for "Read measured value block" function and confirm with Q.

• ‒ Input 00 for "Display group number" and confirm with Q.

• ‒ Note intake air temperature figure in display zone 4.

• ‒ → Spray sender -arrow- with a commercial chilling spray and at the same time observe the temperature figure. The temperature figure must
       increase.

If the display changes:

• ‒ Press ⇒ button.
• ‒ Input 06 for "End output" and confirm with Q.

If the display does not change:

• ‒ Press ⇒ button.
• ‒ Input 06 for "End output" and confirm with Q.

• ‒ Switch off ignition
• ‒ → Pull 4 pin connector -1- off injection unit -2-.
• ‒ Check resistance between contacts 1+4 at socket.
       Specification , Fig. 1
• ‒ Spray sender with chilling agent and observe resistance. The resistance must
       increase.

If the resistance values are not attained or no change is detected:

• ‒ Replace injector bracket with intake air temperature sender (G42) , item 7 .

If the specifications are attained:

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wire between test box socket 43+4 pin connector contact 2 for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wire for short to battery positive, to wire contact 1 and to vehicle earth.
       Specification: ∞ω
• ‒ Check wire between test box socket 17+4 pin connector contact 1 for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω

If no fault in wire is detected:

• ‒ Renew Mono Motronic control unit (J257)
  , item 2 .